Summary of the review of database principles

Summary of the review of database principles

database technology is the main research on how to organize and store data, efficient acquisition and processing of data, and can meet the needs of a variety of users of information technology, because the requirements of the database technology is very large, so learning this course of knowledge and technology is very necessary, should be skilled to understand, master Data , data management, database, data Model and the Conceptual Model the connotation of such professional terms.

The 1th Chapter Introduction

1. Master the concept of database, database management system, database system (composition)

2. Understand the three stages of database technology development

3. Master the concept of three-level and two-level images

4. Understanding the main functions of the database management system

Knowledge Points:

data : The object of database system research and processing, describing the symbol record of world things , has the following four characteristics:

1: Data has "value" and "type" of the points

"Value" refers to the specific numeric value of the data, "type" refers to the structure of the data.

2: Data is constrained by the range and type of values.

3: A qualitative representation and quantitative representation of the points.

4: With a carrier and a variety of forms of expression.

Database: Long-term storage in the computer, organized, shareable, unified management of the data collection, is a data structure to store information in the computer software system.

1: Storage of Data Warehouse, data management of new methods and technologies, can more reasonable organization of data, more convenient and more reasonable maintenance, control, use of data.

The characteristics of a collection of data:

1: Minimum redundancy level.

2: The application is shared with the data resource.

3: High data independence.

4: Unified management and Control .

Database management System (DBMS): computer software that provides data management.

Unified management and control of the database to ensure the security and integrity of the database, the user can access the contents of the database through the DBMS, the database administrator can maintain the data through the DBMS .

Main functions:

1: Data definition capability.

2: Data manipulation capability.

3: Database maintenance capability.

4: Database establishment and maintenance function.

Database system:

Includes computer hardware, database, database management system, application system and database administrator, computer system with database and database management.

The database system has the following characteristics in relation to the file system:

1: The structure of the data.

2: Data redundancy of database system is small, data sharing degree is high.

3: There is a high degree of independence between data and procedures of the database system.

4: The minimum access unit for data in a database is a data item.

5: Unified data management and control.

6: Provide database protection.

The 2nd Chapter Data Modeling

1. Master the representation of the entity Contact Model (E-r chart), including entity, attribute, contact, and contact type.

2. Understanding the three elements of the data model

3. Understanding the characteristics of hierarchical, mesh data models

Knowledge:

Database Common model: 1, Hierarchical Model:

2, mesh model, 3, relational model,4 object-oriented model.

　1. Entities (Entity)
An entity is a thing that exists in the real world. Can be a specific thing, such as a house, a component, a person, etc., can also be abstract things, such as an idea, a plan, or a project, and so on. Entities represent their characteristics by their own property values. Entities are divided into strong entities and weak entities.

　2. Entity set:
A collection of entities with the same structure and attributes is called an entity set. For example, student entity sets, class entity sets, and so on.

3. Entity type:
Describes the information structure of an entity set, typically including a type name and a collection of attribute names for an entity. For example, students (school number, name, gender, age, Class).
　　4. Property:
Describes the attributes of an entity or contact. Each attribute of an entity is called an attribute. Attributes have attribute names, attribute types, attribute definition fields, and attribute values.
　　5. Entity identification (code or key):
The attribute set whose value uniquely identifies each entity is called the identity of the entity. The identity of an entity in a relational database is called a code or key whose identification code is the value of a single attribute or subset of attributes of an entity.
For example, the student's school number, both the student's attribute and the student's identification code, the institute's logo can be the institute's name or the number.
　　6. Contact:
In the real world, the interrelation between things is objective, and the relation reflects the relationship between entities. This connection must be described in the information world. Also, the contact itself can have attribute values in addition to being used as a property.
For example, each teacher is affiliated with a research institute, and each teacher has a subordinate relationship with one of its affiliated institutes.
　　7. Contact Set:
The same type of contact between entities also forms a collection of contacts. For example, multiple teachers and their affiliated institutes form a subordinate contact set.
　　8. Contact Type:
Describes the information structure of a contact set between entities that have a common attribute, usually including the type name of the contact, the properties of the contact, and so on.
For example, each teacher and one of its affiliated institutes is "belonging" to each other, and each teacher and the student he teaches is a link between "teaching and learning", a "supply" link between a part supplier and the parts it supplies, and the properties of the "supply" link are provided.

• Data: The fact that reflects the objective world, and can distinguish its characteristic symbol: character, numeral, text, sound, figure, image, chart, picture, etc., they are the real world existence objectively, can enter into the computer to store and manage. · Information (information): Data that is processed and refined by raw data and used to determine behavior, plan, or have some semantics is called information. · Database db (Data Base): is a collection of interconnected large amounts of data and relationships between data in the real world. · Database management System DBMS (data Base Management system): is a software system for storing and managing data in a database. Includes a variety of languages and tools for storing, managing, retrieving, and controlling data in a database, which is a set of system software. · Database systems DBS (Data Base System): is a generic term for database and database management systems. Refers to a collection of interrelated data sets and software tools that manipulate data. DBS = Db+dbms · Database application Interface API (application programming Interface): is an interface function, procedure, or language that is provided by the DBMS to manipulate and access data in the database for development applications. · Database application AP (application program): A program that satisfies a user's requirements for manipulating and accessing a database. · DW (Data Warehouse) A data warehouse is a business application system with its own database. The use of existing data resources, the data into information, from the mining of knowledge, refined into wisdom, to create benefits. · Data Mining (Mining) Data mining can help business users deal with large amounts of existing data in order to discover "unexpected relationships" in order to increase market share and profitability. · Information Discovery (Information Mining): Information exploration refers to the discovery of information in the vast ocean of documents, maps, photographs, sounds, and images, i.e., content-oriented retrieval. · Data Model: In the database, the description of the data (entity) is called the database schema. Described in the corresponding schema definition language. · Data Model: is the digital simulation and abstraction of real-world features. · Fields (field): The smallest unit of data in a hierarchical data model that describes the attributes of an entity. · Fragment (Segment): is the unit of the entity that is described in the IMS hierarchical data model, a record that consists of a field collection. is also the unit in which the application accesses database data. · Data item: is the smallest unit of data in the DBTG named Mesh data model, representing the attributes of the entity. · Recording (record): is the unit of the DBTG-named mesh data model that describes the entity, which is an ordered collection of data items. · Domains (domain): A field is a collection of values, which is the range of values. · Relationship (Relation): A relationship is a two-dimensional table with one table name per table. · Tuple (tuple): A row in a relational table is called a tuple. A tuple can represent a connection between an entity or an entity. · Properties (Attribute): A column in a relational table is called a property of a relationship, which is a data item of a tuple. Attributes have attribute names, attribute types, attribute value domains, and attribute values. The property name is unique in the table.

· Keyword (Primary key): A combination of one property or several properties in a table whose value uniquely identifies a tuple in the relationship. The keyword attribute cannot take a null value. · External keyword (forgien key): The group of attributes in one relationship that corresponds to the keyword of another relationship is called the external keyword of the relationship. The external keyword takes a null value or is the corresponding key value in the external table. · Network library (net-library): A communication software package that packages database requests and results and is transmitted by network protocols. Also known as Net-library, installed on both the client and the server.

3rdChapter relational database

2. Understanding the 6 properties of the relationship

3. Master the Concept: code, main attribute and non-main attribute, full code and external code, the representation of the relationship mode.

4. Mastering the three types of integrity constraints (Entity integrity, referential integrity, and user-defined integrity) of the relationship

5. Proficient in the use of relational algebra to express various types of queries (set operation, selection, projection, connection, except), the ability to use relational algebra to express query requirements according to the data table structure.

4th Chapter Normalization theory

1. Mastering Concepts: function dependencies, partial function dependencies, full function dependencies, and transfer function dependencies.

4. Mastering the Paradigm Concept: 1NF, 2NF, 3NF

5. Grasp the decomposition methods and procedures of the model, according to the given relationship model, judge its pattern type, and according to the requirements of the decomposition, to achieve the specified paradigm level.

6. Understanding the principles of relational pattern decomposition

5th Chapter Database Design

1.6 Steps to understand database design and how to use it

3. Master the conceptual structure (E-r diagram) Design method, understand the common three kinds of conflicts between the e-r graphs

4. Mastering the rules of E-r diagram to Relationship mode transformation, understanding the optimization of data model

According to the given semantics, we can find the related entity, the entity's attribute, the relation between entities, draw the E-r graph, and can transform to the corresponding relation pattern.

6th Chapter SQL language

1. Data definition language, data query language, Data Update language

2. Concepts of indexes and views

can write the corresponding SQL statements according to the given table structure and query requirements.

7th . Database Security (non-key chapters)

1. Mastering Concepts: The characteristics of transactions and transactions

2. Understand the concept of security control and common methods, master the basic statement of authority Grant and recovery

3. Understanding the concept of integrity control

4. Understand the concept of concurrency control and the inconsistency of the three types of data resulting from concurrency

Understand the concept of blockade, understand the blockade protocol

5. Understanding the concepts and principles of database recovery

Temporarily updated to this,,, tomorrow to fill the rest.

Summary of the review of database principles